It was only when I also stopped server2, that server1 actually stopped.

I would of course, at this point, expect an ITS has been filed, and a
fully detailed gdb backtrace submitted along with it.

I'll try to reproduce something better to post in an ITS. As I said, it
doens actually crash, it just hangs.
I can see with tcpdump, that server1 actually tries to connect once
every minute to server2 and does establish an TLS connection, but after
af few frames of application data it sends close notify.
Another thing bothering me is that a few threads on server1 are using
99.9% CPU.

(server2 is not accessed by clients, so it is mostly idle)

Is it possible to temporarily turn of mirroring of cn=config, so I can
raise loglevels on server2 without the change being replicated to
server1 and thus hanging the whole system ?

What happens if I just turn "mirrormode off" on server2 for a while?
/Peter